The present invention relates to a peripheral pump for feeding fuel from a supply tank to an internal combustion of a motor vehicle.
More particularly, it relates to such a peripheral pump which has an impeller provided with a plurality of vanes and rotatable in a pump chamber limited by walls provided with supply passages.
Peripheral pumps of the above mentioned general type are known in the art. One of such peripheral pumps is disclosed for example in the German document DE 40 36 309 A1. The peripheral pump operates for feeding fuel from a supply tank to an internal combustion engine of a motor vehicle and has an impeller with vanes distributed over its both end surfaces. The pump chamber in which the impeller rotates is limited in direction of the rotary axis of the impeller by a wall part and in radial direction by a housing part. End sides of both wall parts which face the impeller are provided with a substantially ring-shaped supply passage, and both supply passages extend radially outwardly farther than the impeller and connected with one another over the outer periphery of the impeller. A suction opening is formed in one wall part and opens in the supply passages formed in this wall part identified as a front supply passage. The front supply passage is formed as a full passage in the region of the suction opening. The other wall part is provided with a pressure opening which leads from the supply passage formed in this other wall part outwardly and identified as a rear supply passage. The supply passages have a trapezoidal cross-section and an overflow connection of the rear supply passage with the suction opening is provided in the region of the suction opening. The overflow connection is limited outwardly by a wall extending substantially parallel to the rotary axis of the impeller and also limited with respect to the suction opening by a wall which is inclined to the rotary axis. The transition of the parallel wall to the inclined wall is arranged near the end side of the impeller which faces the suction opening, as considered in direction of the rotary axis of the impeller.
In the region of the suction opening fuel flows both in the front passage formed in the wall part which faces the suction opening, and also through the overflow connection over the periphery of the impeller, into the rear supply passage formed in the other wall part. The fuel which flows into the supply passages is displaced by the impeller to form whirls, and fuel flows from the rear supply passage back to the suction opening and into the front supply passage. Moreover, during inflow of the fuel into the supply passages, the arrangement of the inclined wall of the overflow region forms whirls, so that the fuel does not flow into the rear supply passage but instead flows again back to the suction opening or to the front supply passage. Thereby the efficiency of the peripheral pump is reduced.